Soil stabilization apparatus

ABSTRACT

Apparatus is described which makes it possible to utilize old asphalt and asphalt/concrete traffic bearing surfaces in forming a stabilized base for a new traffic bearing surface. Basically, the apparatus of the invention comprises a vehicle having a transversely extending cutting blade mounted in a location to sever an upper layer of the material over which it is traveling from the remainder of the material and feed such layer rearwardly relative to the traveling vehicle to a pulverizing and mixing rotor also extending transversely of the apparatus. Besides pulverizing an old traffic bearing surface, the rotor mixes same with soil and a soil stabilizing medium such as lime or cement. The degree of pulverization and mixing, as well as the thickness of the surface layer removed, is controllable.

United States Patent 1 Rank et al.

May 3, 1973 SOIL STABILIZATION APPARATUS [75] Inventors: Carleton L.Rank, Walnut Creek; Ray T. Ryan, San Rafael, both of Calif.

[73] Assignee: Metradon Associates, Lafayette,

Calif.

22 Filed: Mar. 11, 1969 [21] App1.No.: 806,121

[52] US. Cl .,...404/90,404/92,404/l I l [51] ..E0lc 19/02 [58] Field ofSearch...... .94/39, 40, 44;

[56] References Cited UNITED STATES PATENTS 1,883,667 10/1932 Flynn..94/39 UX 2,090,290 8/1937 Gardner..

2,473,770 6/1949 Seaman 3,224,347 12/1965 Seaman...

3,318,209 5/1967 Schultz ..94/50 Primary Examiner-Nile C. Byers, Jr.AttorneyGardner & Zimmerman [57] ABSTRACT Apparatus is described whichmakes it possible to utilize old asphalt and asphalt/concrete trafficbearing surfaces in forming a stabilized base for a new traffic bearingsurface. Basically, the apparatus of the invention comprises a vehiclehaving a transversely extending cutting blade mounted in a location tosever an upper layer of the material over which it is traveling from theremainder of the material and feed such layer rearwardly relative to thetraveling vehicle to a pulverizing and mixing rotor also extendingtransversely of the apparatus.

Besides pulverizing an old traffic bearing surface, the rotor mixes samewith soil and a soil stabilizing medium such as lime or cement. Thedegree of pulverization and mixing, as well as the thickness of thesurface layer removed, is controllable.

4 Claims, 12 Drawing Figures PATENTEDMY 8 ma SHEET 2 OF 3 IVNTORS EVA NAffOkWE rs CAELETON L. RANK FAY 7:

SOIL STABILIZATION APPARATUS BACKGROUND OF THE INVENTION This inventionrelates to earth working machinery and, more particularly, to a soilstabilizing and pulverizing apparatus especially adapted for use in theconstruction of traffic bearing surfaces such as roadways and airportrunways.

When a heavy traffic bearing asphalt or asphalt/concrete surface, suchas the surface of a highway or airport runway, is to be renewed, thecommon practice is to first rip up the old hard surface and haul thechunks thereof away. Then the substrate or road base is stabilized toincrease its density, such as by mixing the same with a lime or cementslurry. After the base has been brought up to a requisite density andhardness, an asphalt mixture, concrete, or other suitable material isthen applied over the base to form the new traffic bearing surface.

It will be appreciated that the hauling away of the old traffic bearingsurface constitutes a major expense in the road renewal process. Notonly is the cost of trucking the material high, particularly when itmust be trucked to a distant location, but the time involved in theremoval of the old roadway adds greatly to the labor and total expense.

SUMMARY OF THE INVENTION The instant invention is an apparatus whicheliminates the necessity of removing an old asphalt or asphalt/concretetraffic bearing surface before a new traffic bearing surface can beformed and, in fact, utilizes the old surface to provide anexceptionally well stabilized base for the new roadway. Moreparticularly, the instant invention is capable of pulverizing in situasphalt and asphalt/concrete surfaces and mixing the pulverized materialwith lime, cement, or emulsified asphalt to create the stabilized basefor the new roadway. In its basic aspects, the invention comprises avehicle adapted to travel over a material surface such as an old trafficbearing surface. A cutting and lifting blade is mounted on the vehiclewith a horizontal front cutting edge located to cut a layer of thematerial from the surface and direct the same rearwardly over such bladeto a mixing and pulverizing rotor having cutting teeth for engaging thelayer of material to chop and mix the same. The cutting of the surfacelayer of the material by the blade from the road, and the relationshipof the cutting blade to the rotor are important in providing the degreeof pulverization of the material necessary for its reuse in forming thenew road bed. As will be described hereinafter, the degree ofpulverization and mixing obtained, as well as the thickness of the layerpulverized, is controllable. The specific design of the rotor and itsteeth are also important in assuring that the necessary mixing andpulverization is obtained.

The instant invention therefore eliminates the necessity of hauling oldtraffic bearing surfaces away before new ones can be provided. Moreover,it utilizes the old roadway to provide an enhanced stabilized base forthe new roadway. In fact, the stabilization obtained with the instantinvention and its use of the old roadway is sufficiently great that inmany applications it is not necessary to apply a new layer of asphalt,oil or cement or the like to provide the traffic bearing surface. Thestabilized base obtained with use of the instant invention is hard andstable enough for use as the traffic bearing surface itself.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. I is an overall side elevational view of a preferred embodiment ofthe instant invention with portions thereof broken away and shown insection;

FIG. 2 is a rear elevational view of the preferred embodimentillustrated in FIG. 1 with the upper portion thereof broken away;

FIG. 3 is a top plan view of the apparatus of FIG. 1 showing the same ina reduced scale and with portions broken away;

FIG. 4 is a front broken away cross-sectional view taken on a planeindicated by lines 4l4 in FIG. 3 and illustrating details of theconstruction of the apparatus;

FIG. 5 is an enlarged partial cross-sectional view taken on the planeindicated by the lines 5-5 in FIG.

FIG. 6 is a partial cross-sectional view taken on a plane indicated bythe lines 66 in FIG. 5 and illustrating one of the teeth of the rotor inedge elevation;

FIG. 7 is a partial cross-sectional view taken on the plane indicated bylines '77 in FIG. 6 and showing the tooth of FIG. 6 in side elevation; 7

FIG. 3 is a partial cross-sectional view on a plane indicated by thelines 8-8 in FIG. 5 illustrating another one of the teeth of the rotor;

FIG. 9 is a partial end view illustrating certain aspects of theconstruction of the apparatus;

FIG. 10 is a partial side elevational view depicting a preferred mannerby which the cutting blade is adjustable relative to the rotor;

FIG. 11 is a partial cross-sectional view illustrating an alternatemeans of adjusting the cutting blade relative to the rotor; and

FIG. 12 is a partial cross-sectional view taken on a plane indicated bythe lines 12l2 in FIG. 11 and depicting further details of the alternateembodiment shown in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings,particularly FIG. I, it will be seen that the stabilizing andpulverizing apparatus of the invention comprises a vehicle 10 adapted totravel over a material surface such as over an old traffic bearingsurface. More particularly, the vehicle I0 includes a main frame 11having adjacent its rear end a plurality of soft tire wheels 12 andextending forwardly from its front end a heavy duty pulling tongue 13.As is shown, tongue 13 includes at its free end a mount 14 allowinguniversal movement of tongue 13 relative to the draw bar 16 of a pullingtractor 18 or the like. As is shown, a tank trailer 19, for purposessubsequently to be described, may be secured to the rear of vehicle 10by means of a suitable conventional hitching arrangement 20 for traveltherewith.

The apparatus of the invention is adapted to cut a layer of materialfrom the surface over which it is traveling and mix and pulverize thesame. More particularly, the apparatus includes a carriage, generallyreferred to by the reference numeral 21, which supports a cutting andlifting blade 22 in a horizontal position transversely of the apparatusin a location at which it can be made to extend beneath the surface ofthe material. As is best illustrated in FIG. 4, blade 22 is defined by aplurality of closely adjacent or overlapping teeth 23, the forward edge24 of each of which is sharpened to provide for the full cutting blade agenerally horizontally extending front cutting edge. As the apparatus ofthe invention travels over a material with the blade lowered thereinto,the front cutting edge of the blade acts to sever an upper layer of thematerial from the remaining material. As is illustrated, blade 22extends angularly upward somewhat from its cutting edge. Therefore, asthe blade travels through the material, it not only directs the severedlayer rearwardly relative to the apparatus, but also lifts the severedlayer from the remaining material.

Means are provided on the apparatus for mixing and pulverizing the layerof material severed by cutting blade 22. More particularly, a mixing andpulverizing rotor, generally referred to by the reference numeral 26, ismounted on carriage 21 widthwise of the vehicle rearwardly of the bladecutting edge at a location at which cutting teeth 27 thereof engage thematerial passed over the blade and chop and mix the same. As is bestillustrated in FIG. 4, rotor 26 includes a central rotor shaft 28 whichextends transversely of the vehicle in a generally horizontal plane andis suitably journaled within bearings (not shown) in side plates 29 ofcarriage 21. A plurality of rotor discs 31 are mounted coaxially onshaft 28 in equally spaced apart relationship. As shown, discs 31 act assupports for teeth 27, each of which extends generally radially outwardfrom its associated disc.

As has been mentioned previously, the invention is particularly suitedfor the pulverization of old asphalt and asphalt/concrete trafficbearing surfaces. It will be appreciated that because of the hardness ofsuch surfaces, the design of the rotor and the cutting blade and theirrelationship are important in assuring the desired pulverization andmixing of materials. In this connection, FIGS. 6 through 8 illustrate atooth design which has been found to be particularly effective in thecombination to provide the pulverization and mixing. With referencefirst to FIGS. 6 and 7, it will be seen that tooth 27 includes a cuttingportion 32 which is generally wedge shaped to define a triangular edgesurface 33 which is normal to the disc 31 with which such tooth isassociated. Triangularly shaped edge surface 33 thereby acts as thecutting edge of the tooth which engages the layer of material duringrotation of the rotor.

Each tooth 27 is mounted to its associated disc 31 in a manner whichpermits quick release of the tooth if it becomes necessary, andsubstitution therefor of a new tooth. More particularly, the mountingmeans for each tooth includes a rectangular channel shaped holder 34which extends radially outward from its associated disc 31 and issuitably secured thereto such as by welding. Each of the teeth 33includes a shank portion 36 which fits snugly within the cavity of itsassociated holder. As is best illustrated in FIG. 7, the shank 36 ofeach tooth includes an open ended slot 37 which extends longitudinallyinto the shank from its free end, and the inner side surfaces of slot 37are provided with opposing circular shaped recesses which register withan aperture extending through holder 34. A split bolt 38 of the typehaving a resilient central portion 39 extends through the aperture inholder 34 and a pair of the opposed recesses in tooth 27 to therebysecure such tooth within the holder. It will be appreciated that withthis construction each of the teeth 27 may be released from the holderby simply driving the pin 38 therefrom, and a replacement tooth may besecured to the rotor by merely inserting its shank into the holdercavity and driving the pin 38 through the registering apertures in theholder and cooperating recesses in the tooth.

As will be noted, there are four teeth secured to each disc at regularangles. Moreover, the location of the teeth on each disc is angularlyoffset a small amount from the location of the teeth on adjacent discsso that, as will be seen from FIG. 4, the teeth are spirally arrangedtransversely of the rotor. This equal spacing and spiral arrangement ofthe teeth assures that the loads imparted to the rotor as the teethengage the layer of material to be mixed and pulverized are generallyuniform throughout each full revolution of the rotor.

Every alternate tooth on each disc is mounted on the disc to extend, asshown in FIG. 8, angularly toward an adjacent disc to assure contact ofsuch tooth with material passing between the planes of such discs. Moreparticularly, the cavity within the holder 34' of each alternate tooth27 is angled transversely away from the plane of the disc to which suchholder is secured. The result is that when tooth 27 is secured withinsuch cavity, the tooth will also be angled away from the plane of thedisc and thus project into the area between the planes of the disc withwhich it is associated and of one of its adjacent discs. It should benoted that all of the teeth 27 are canted in the same direction andsubstantially the same amount.

Because of the hardness of old traffic bearing surfaces, it will beappreciated that a high horse power and torque driving means isnecessary to rotate rotor 26. In this connection an internal combustionengine 41 is suitably mounted on the upper portion of main frame 11 ofthe apparatus. Engine 41 drives through a suitable transmission 42 anoutput shaft 43 having mounted thereon a plurality of belt pulleys 44.Pulleys 44 are coupled by means of the belt 46 to corresponding pulleys47 on one end of an idler shaft 48 which extends transversely ofcarriage 21 rearwardly of rotor 26. Shaft 48 is suitably journaledwithin opposite sidewalls 29 of carriage 21 and also to flanges 50 onopposite sides of main frame 11. A second set of pulleys 49 on shaft 48adjacent pulleys 47 are coupled by means of belts 51 to pulleys 52 on anend of rotor shaft 28 extending outwardly of the adjacent flange 50. Asuitable fuel tank 53 for engine 41 is mounted on frame 11 adjacent tosuch engine.

It will be readily apparent from the above that the driving arrangementand coupling discussed will cause the output of engine 41 to rotaterotor 26. The belt and pulley arrangement allows slippage between theengine and the rotor if for some reason the rotation of such rotor ishindered such as because of engagement with rocks or the like.

Means are provided for adjusting the depth to which the cutting blade 22extends beneath the surface of the material to be stabilized and, hence,the thickness of the layer being fed to rotor 26. For this purpose, thecarriage 21 carrying cutting blade 22 and rotor 26 is mounted adjacentits rear end flanges 50 of main frame 1 1 by idler shaft 48. In thisconnection, sidewalls 29 of carriage 21 are rigidly secured together forsimultaneous movement by suitable supporting structure including atransversely extending boxchannel 54 beneath cutting blade 22 andadjacent their forward upper ends by a transversely extending tubularstructural member 56.

Hydraulic means are provided for pivoting carriage 26 about shaft 48 tothereby raise and lower cutting blade 22 with respect to main frame ofthe apparatus.

That is, a hydraulic pump and reservoir 57 mounted on frame 11 forwardlyof engine 41 is siiitably'connected by means of lines 58 with ahydraulic cylinder 59. The free end of piston rod 61 of cylinder 59 issecured by linkage 62 mounted on frame 11 and connected to tubular crossmember 56 of carriage 21 for pivoting such carriage about shaft 48 uponextension and retraction of rod 61. A supporting rod and chain 63 isalso provided for supporting carriage 21 in selected positions, tothereby reduce the strain on the hydraulic system during use of theapparatus.

Further control of the depth to which blade 22 extends into the materialbeing worked can also be obtained by pulling the apparatus with atractor having a draw bar as shown whose vertical position can beadjusted. In the illustrated arrangement, draw bar 16 is hydraulicallyoperated by means of a pair of adjacent jacks, one of which is denotedat 64 in FIG. 1. It will be appreciated that raising and lowering ofdraw bar 16 will pivot the frame 1 1 about the axle of the groundengaging wheels 12 with a consequent raising and lowering of cuttingblade 22 relative to the material surface. If an embodiment of theinvention is always to be pulled by a tractor having such an adjustabledraw bar, the separate hydraulic adjusting means mounted on theapparatus as described above is not necessary. However, it is preferredthat it be included so that no undue limitations are placed on the typeof pulling vehicle which can be utilized with the apparatus.

In some instances, it is desirable to provide means to assist blade 22in the feeding of the material to rotor 26. In the embodiment of theinvention illustrated, an auxiliary feed roller 66 is mounted oncarriage 21 above blade 22 for this purpose. Feed roller 66 includes ashaft 67 which extends between carriage side walls 29 and is suitablyjournalled therein for rotation. A plurality of feed paddles 68 extendradially outward from shaft 67 for engagement with material severed byblade 22 to aid in feeding such material rearwardly to rotor 26. Ahydraulic motor 69 (FIG. 3) mounted on the exterior side of one of theplates 29 has its output connected to shaft 67 for rotating the same.Hydraulic pressure to drive motor 69 may be suitably provided in aconventional manner such as from pump 57. Since feed roller 68 is notnecessary or desirable for feeding all materials, it is removablysecured to the carriage. In this connection, as shown in FIG. 5, shaft67 is mounted between plates 29 by a conventional split bearing 69.

As a particularly salient feature of the invention, means are providedfor controlling the degree of pulverization of the material fed to rotor26. This is important since the amount of stabilization which can be obtained with various old traffic bearing compositions depends on themaximum size of the particles of the old composition which are mixedwith other stabilizing materials such as lime or cement. The degree ofpulverization of the layer of material passing over cutting blade 22 isdependent upon the amount of space between the cutting blade and theteeth of rotor 26. To control the degree of pulverization, therefore,the distance between the cutting blade and rotor is adjustable. Moreparticularly, with reference to FIGS. 5, 9 and 10, it will be seen thatcutting blade includes a forward portion defined by the teeth 23 whichis rigidly secured between side walls 29 of the carriage such as bybeing bolted to channel cross member 54 by bolts 71. The rear portion ofblade 22, however, is comprised of a plate 72 which is supported forslidable movement with respect to the remainder of the cutting blade byblocks 73 riding in slots 74 in the opposite side walls 29 of carriage211. As illustrated, the forward portion of plate 72 is supportedbeneath the blades 23 by spaced apart supports 76 projecting rearwardlyfrom channel 54 to def ne a slot for plate 72 between the supports andthe rear portion of the teeth 23. A hydraulic cylinder 77 is mounted onthe outside of each of the side walls 29 and has its piston rod 78suitably secured to the block 73 within the slot 74 in its associatedside wall 29. Cylinders 77 are conventionally in communication withhydraulic pump 57 so that their piston rods 76 may be simultaneouslyextended or retracted to move plate 72 longitudinally relative to theteeth 23 of the cutting blade.

The above arrangement provides the desired means of adjusting thedistance between the cutting blade 22 and the rotor teeth. That is, withreference to FIG. 5, it will be seen that upon retraction of the pistonrods 78 to slide a portion of plate 72 out from beneath teeth 23, thedistance between plate 72 and the teeth 27 and 27 on the discs 31 willbe lessened. The result is that there is less room for material to passbetween the rotor and the blade, with the consequence that the materialmust be pulverized to a finer degree before it can pass between theblades and rotor. However, upon extension of piston rod 78, the plate 72will be slid beneath the teeth 23 to thereby enlarge the space betweenthe rotor and the cutting blade. The result is that the material neednot be pulverized to as great an extent to pass between the blade androtor and, therefore, larger particles of the old traffic bearingsurface will be provided.

FIGS. 1 l and 112 show another arrangement permitting adjustment of thedistance between the rotor and the cutting blade. In this embodiment,the blocks 73 which are secured to the ends 78 of the piston rods 77 aresecured directly to the cutting blades 23. The channel 541 acts as asupport for such blades, but such blades are slidable with respectthereto. A plurality of spaced apart flange plates 81 extendlongitudinally outward from channel 54 to provide further support forblades 23. It can be seen that with this construction the blades 23)themselves are movable forwardly and rearwardly with respect to therotor to change the distance therebetween for the purposes discussedabove. It will be appreciated that with this arrangement it may benecessary to adjust the vertical location of blade 22 by means of thehydraulic jack 59 or the draw bar 116 to as sure that blade 22 iscutting to the required depth after its location relative to the rotorhas been varied.

In some situations the teeth 27 and 27 will wear fairly rapidly due tothe hardness of the material being pulverized and mixed. The length ofsuch teeth therefore decreases, and to maintain the same distancebetween the teeth and the cutting blade it may be necessary to adjustthe distance as described above. It will be further noted that while itis preferred that the cutting blade be adjustable in order to adjust thedistance between the rotor and the blade, the location of the rotor maybe made adjustable for the same purpose if desired.

In the use of certain materials for providing a stabilized bed for atraffic bearing surface, it is desirable to be able to mix the materialbeing stabilized with a liquid at the time it is being pulverized andmixed by rotor 26. As is best illustrated in FIGS. 4 and 5, theapparatus of the invention includes a liquid distribution pipe 82extending transversely between side walls 29 of carriage 21 at alocation above the axis of rotation of rotor 26. Distribution pipe 82 isprovided with a plurality of downwardly pointed orifices 83 spaced apartalong its length. A suitable liquid, such as water, may be sup plied topipe 82 by means of a rearwardly extending flexible conduit 84 which isas shown in FIG. 1 in communication with tank trailer 19 hitched to theapparatus of the invention for movement therewith. A suitable pump (notshown) is mounted on tank trailer 19 for forcing liquid through conduit84 and, hence, through orifices 83 of distribution pipe 82.

In the stabilization of a base for a traffic bearing surface, a layer oflime or cement 86 is first applied over the material with which it is tobe mixed to form the stabilized base. In the environment illustrated inFIG. 2, the layer 86 is provided over an old traffic bearing surface,denoted by numeral 87. With some old traffic bearing surfacecompositions, it is desirable before the layer 86 is applied to rip upthe old surface with a suitable ripping mechanism to facilitate itspulverization by the apparatus of the invention. Then the apparatus ofthe invention is utilized to mix the layer of stabilizing material 86with the old traffic bearing surface 87 and the underlying soil toprovide the stabilized base for the new surface. After passing betweenrotor 26 and cutting blade 22, the material will be discharged onto thesurface from which it has been cut to provide a new top layer threrfor.The apparatus of the invention includes means rearwardly of carriage 21for leveling or smoothing the surface of the discharged material. Thatis, a leveling plate 88 is mounted on frame 11 transversely of theapparatus at a location immediately forward of wheels 12. The height ofplate 88 relative to the apparatus can be adjusted by means of ahydraulic jack and linkage system 89 so that the height of the finishedstabilized bed is controllable.

We claim:

1. A soil stabilizing and pulverizing apparatus com prising a vehicleadapted for travel over a material surface, a cutting and lifting blademounted on said vehicle with a generally horizontally extending frontcutting and pulverizing rotor mounted width-wise of said vehiclerearwardly of said cutting edge and having cutting teeth projectinggenerally radially outward from said rotor for engagement with the layerof material passed over said blade to chop and mix the same, thedistance between the rotor teeth and said blade being adjustableindependently of said blade depth to provide a selected maximum size tothe particles of material discharged from between said rotor teeth andblade, and a feed roller mounted transversely of said vehicle above saidcutting blade to assist said blade in feeding said layer of materialrearwardly of said cutting edge and towards said rotor.

2. A soil stabilizing and pulverizing apparatus comprising a vehicleadapted for travel over a material surface, a cutting and lifting blademounted on said vehicle with a generally horizontally extending frontcutting edge located to cut a layer of said material from said surfaceand direct same rearwardly and upwardly over said blade, means forselectively altering the depth to which the cutting edge of said bladeprojects beneath the surface of said material to thereby change thethickness of the layer cut from said material, a mixing and pulverizingrotor mounted width-wise of said vehicle rearwardly of said cutting edgeand having cutting teeth projecting generally radially outward from saidrotor for engagement with the layer of material passed over said bladeto chop and mix the same, the distance between the rotor teeth and saidblade being adjustable independently of said blade depth to provide aselected maximum size to the particles of material discharged frombetween said rotor teeth and blade, and means for varying the locationof said cutting blade in the general plane thereof and relative to saidrotor to provide said distance adjustment.

3. The soil stabilizing and pulverizing machine according to claim 2wherein said cutting blade includes a plate extending transversely ofsaid vehicle and movable longitudinally relative thereto toward and awayfrom said rotor to provide said distance adjustment.

4. The soil stabilizing and pulverizing machine of claim 2 wherein saidrotor includes a rotor shaft extending transversely of said vehicle in agenerally horizontal plane and a plurality of rotor discs spaced apartcoaxially along said shaft and normal thereto, each of said discs havinga plurality of equally spaced apart teeth projecting radially outwardtherefrom and towards said blade for engagement with said material. eachof said teeth including a shank portion fitted within a channel shapedholder rigidly secured to the disc with which said tooth is associated,said tooth being secured within said holder by a split bolt passingthrough said holder and said tooth.

1. A soil stabilizing and pulverizing apparatus comprising a vehicleadapted for travel over a material surface, a cutting and lifting blademounted on said vehicle with a generally horizontally extending frontcutting edge located to cut a layer of said material from said surfaceand direct same rearwardly and upwardly over said blade, means forselectively altering the depth to which the cutting edge of said bladeprojects beneath the surface of said material to thereby change thethickness of the layer cut from said material, a mixing and pulverizingrotor mounted width-wise of said vehicle rearwardly of said cutting edgeand having cutting teeth projecting generally radially outward from saidrotor for engagement with the layer of material passed over said bladeto chop and mix the same, the distance between the rotor teeth and saidblade being adjustable independently of said blade depth to provide aselected maximum size to the particles of material discharged frombetween said rotor teeth and blade, and a feed roller mountedtransversely of said vehicle above said cutting blade to assist saidblade in feeding said layer of material rearwardly of said cutting edgeand towards said rotor.
 2. A soil stabilizing and pulverizing apparatuscomprising a vehicle adapted for travel over a material surface, acutting and lifting blade mounted on said vehicle with a generallyhorizontally extending front cutting edge located to cut a layer of saidmaterial from said surface and direct same rearwardly and upwardly oversaid blade, means for selectively altering the depth to which thecutting edge of said blade projects beneath the surface of said materialto thereby change the thickness of the layer cut from said material, amixing and pulverizing rotor mounted width-wise of said vehiclerearwardly of said cutting edge and having cutting teeth projectinggenerally radially outward from said rotor for engagement with the layerof material passed over said blade to chop and mix the same, thedistance between the rotor teeth and said blade being adjustableindependently of said blade depth to provide a selected maximum size tothe particles of material discharged from between said rotor teeth andblade, and means for varying the location of said cutting blade in thegeneral plane thereof and relative to said rotor to provide saiddistance adjustment.
 3. The soil stabilizing and pulverizing machineaccording to claim 2 wherein said cutting blade includes a plateextending transversely of said vehicle and movable longitudinallyrelative thereto toward and away from said rotor to provide saiddistance adjustment.
 4. The soil stabilizing and pulverizing machine ofclaim 2 wherein said rotor includes a rotor shaft extending transverselyof said vehicle in a generally horizontal plane and a plurality of rotordiscs spaced apart coaxially along said shaft and normal thereto, eachof said discs having a plurality of equally spaced apart teethprojecting radially outward therefrom and towards said blade forengagement with said material, each of said teeth including a shankportion fitted within a channel shaped holder rigidly secured to thedisc with which said tooth is associated, said tooth being securedwithin said holder by a split bolt passing through said holder and saidtooth.